When an application needs to access a file, it must first open it using fs_fopen() or FSFile_Open(). For most applications, the former with its familiar interface suffices. In some cases, the flexibility of the latter is demanded (see ).
The return value of FSFile_Open() should always be verified as non-NULL before the application proceeds to access the file. The second argument to this function is a logical OR of mode flags:
FS_FILE_ACCESS_MODE_RD
File opened for reads.
FS_FILE_ACCESS_MODE_WR
File opened for writes.
FS_FILE_ACCESS_MODE_CREATE
File will be created, if necessary.
FS_FILE_ACCESS_MODE_TRUNC
File length will be truncated to 0.
FS_FILE_ACCESS_MODE_APPEND
All writes will be performed at EOF.
FS_FILE_ACCESS_MODE_EXCL
File will be opened if and only if it does not already exist.
FS_FILE_ACCESS_MODE_CACHED
File data will be cached.
For example, if you wanted to create a file to write to if and only if it does not exist, you would use the flags
FS_FILE_ACCESS_MODE_WR | FS_FILE_ACCESS_MODE_CREATE | FS_FILE_ACCESS_MODE_EXCL
It is impossible to do this in a single, atomic operation using fs_fopen().
The table below lists the mode flag equivalents of the fs_fopen() mode strings.